diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6a845a47..ef062f1f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,9 @@
+Version 165:
+
+* Fix BOOST_NO_CXX11_ALLOCATOR check
+
+--------------------------------------------------------------------------------
+
 Version 164:
 
 * Fix masking on continuation frames
diff --git a/include/boost/beast/core/detail/allocator.hpp b/include/boost/beast/core/detail/allocator.hpp
index 39b2aa5f..e893f5c2 100644
--- a/include/boost/beast/core/detail/allocator.hpp
+++ b/include/boost/beast/core/detail/allocator.hpp
@@ -11,7 +11,7 @@
 #define BOOST_BEAST_DETAIL_ALLOCATOR_HPP
 
 #include <boost/config.hpp>
-#if BOOST_NO_CXX11_ALLOCATOR
+#ifdef BOOST_NO_CXX11_ALLOCATOR
 #include <boost/container/allocator_traits.hpp>
 #else
 #include <memory>
@@ -25,7 +25,7 @@ namespace detail {
 // implementations which falsely claim C++11
 // compatibility.
 
-#if BOOST_NO_CXX11_ALLOCATOR
+#ifdef BOOST_NO_CXX11_ALLOCATOR
 template<class Alloc>
 using allocator_traits = boost::container::allocator_traits<Alloc>;